The present application relates to a structure-defining material for organic light-emitting devices (OLEDs). OLEDs use electro-luminescent organic materials, for example, to provide lighting elements for display devices. OLEDs may be designed to replace conventional non-organic display technologies or for new applications.
A typical OLED display device has a “sandwich” or layered construction. To construct a typical OLED, first, a transparent conducting layer is deposited onto a transparent substrate. The transparent conducting layer typically comprises a transparent conducting oxide material, e.g., indium-tin oxide (ITO). Other materials, including thin metal films, alternatively may be used for the transparent conducting layer. The transparent conductive layer may serve as one of the electrode layers (typically the anode) of the OLED. Next, a set of one or more organic layers is deposited onto the transparent conducting layer. The depositing techniques used may depend on the types of organic material deposited. The organic layers may serve various functions such as hole injecting, hole transporting, electron injecting, electron transporting, and/or as emitting or intermediate layers. Finally, one or more conducting layers are deposited and may serve as another electrode layer (typically the cathode) of the OLED device. Typically, this second electrode layer has a sub-layer formed of a low work function metal (e.g., Ca, Mg, Ba or Li), and a capping sub-layer of a more air-stable high work-function metal (e.g. Ag or Al). Other types of material for the second electrode layer, such as metal alloys or combinations of insulating and metal sub-layers, may be used.
In operation, a voltage is applied across the electrode layers, charge carriers are injected into the organic layers, recombination takes place, and part of the recombination energy leaves the device as photons. The photons pass through the transparent first electrode layer and substrate and are visible as emitted light.